The present invention relates to novel crystalline fumaric acid salts of N,N'-disubstituted 9,9-alkylene-3,7-diazabicyclo[3.3.1]nonane compounds corresponding to the general formula I ##STR1## in which A denotes an alkylene chain of 4-5 carbon atoms and R.sup.1 and R.sup.2 independently of one another each denote a straight-chain or branched alkyl group of 3-4 carbon atoms or the cyclopropylmethyl group.
9,9-Alkylene-3,7-diazabicyclononane compounds of formula I and their pharmacological activities are known from published European Patent No. EP 103,833 and the corrosponding U.S. Pat. No. 4,550,112, and Finnish Patent No. FI 76,338. compounds of formula I are a sub-group of the 9,9N,N'-tetrasubstituted 3,7-diazabicyclo[3.3.1]-nonane compounds described in the aforementioned patent specifications and can be prepared by the methods described therein. The aforementioned patent specifications disclose that the compounds have useful cardio-active properties, particularly oxygen-saving effects and effects on the heart rate and heart rhythm, and are distinguished by a high physiological tolerance. Thus, the compounds show a satisfactory antiarrhythmic action even at low doses. Moreover, the undesired negative effect on the contractile power of the heart is extremely low; i.e. the compounds have a particularly favorable ratio of antiarrhythmic or the refractory period of the heart prolonging activities, to negative inotropic secondary activities.
Moreover, it is described in Burow et al., U.S. Pat. No. 5,164,401, the compounds also have a pronounced diuretic effect with a favorable ratio between sodium and potassium excretion.
Salts of compounds of formula I described in Finnish Patent No. FI 76,338, include the dihydrogentartrate, and in copending U.S. patent application Ser. No. 07/714,886, the dihydrogentartrate and the dihydrochloride of N,N'-dicyclopropylmethyl-9,9-tetramethylene-3,7-diazabicyclo[3.3.1 ]-nonane and the dihydrogentartrate and the dihydrogenfumarate of N-isobutyl-N'-isopropyl-9,9-pentamethylene-3,7-diazabicyclo[3.3.1]nonane.
The salts of the compounds of the formula I used in the past have the disadvantage that they are not obtained in crystalline form. Instead, they are obtained in amorphous form as, for example, the hydrogentartrates, and/or are strongly hygroscopic as, for example, the hydrochlorides. Because of varying solvent contents in salts of this type, it is not possible without special precautionary measures to assure a constant stoichiometric composition and a constant bioavailability.